There is a high demand in medium-voltage power systems for efficient high-voltage power transistors. A power switching module built with gallium nitride (GaN) High Electron Mobility Transistors (HEMTs) can reduce the conduction and switching losses of transistors because GaN HEMTs have lower on resistance (Ron) and less device total charge. The major problem with GaN HEMTs is that their breakdown voltage is relatively low compared to Si and SiC MOSFETs or IGBTs, which limits the utilization of GaN HEMTs in low-voltage applications. That is, there are currently no efficient and compact GaN transistors available with a high voltage rating.